FWIW, this patch is also required to build with not-yet-released GCC 4.7, where you get something like:
In file included from /home/froydnj/src/mozilla-central/hal/Hal.h:45:0,
from /home/froydnj/src/mozilla-central/hal/sandbox/SandboxHal.cpp:40:
../dist/include/nsTArray.h: In instantiation of 'AutoInfallibleTArray<E, N>::AutoInfallibleTArray(const nsTArray<E, Allocator>&) [with Allocator = nsTArrayDefaultAllocator; E = unsigned int; unsigned int N = 8u]':
/home/froydnj/src/mozilla-central/hal/sandbox/SandboxHal.cpp:65:44: required from here
../dist/include/nsTArray.h:1315:5: error: 'AppendElements' was not declared in this scope, and no declarations were found by argument-dependent lookup at the point of instantiation [-fpermissive]
../dist/include/nsTArray.h:1315:5: note: declarations in dependent base 'nsTArray<unsigned int, nsTArrayInfallibleAllocator>' are not found by unqualified lookup
../dist/include/nsTArray.h:1315:5: note: use 'this->AppendElements' instead
I can verify that this bug is fixed with the provided patch.